The reticulocyte count has been conventionally determined using a visual method. Recently, due to technological advances an automated method has come into general use in laboratories. The precision in terms of reproducibility of automated reticulocyte counters has also made rapid progress compared with the visual method. The measurements of reticulocyte counts showed good correlation among the five automated reticulocyte counters and the visual method although the accuracy of an automated method is problematical since it is not sufficient to find the true value. It remains difficult to standardize reticulocyte counting because automated reticulocyte counting is performed in accordance with the procedure specified by the respective manufactures; thus, an external quality control survey was performed for an accuracy assurance of reticulocyte counts with the participation of many laboratories. In the future, it is necessary to develop biological reference materials equal to the true value or to establish other standardization using new technology.